Diabetes is a life-threatening metabolic disease, afflicting around 3% of the world population. Over 90% of the diabetic populations are diagnosed with type-2 diabetes (T2D) mellitus. The current anti-hyperglycemic drugs are insulin secretagogues, insulin sensitizers, inhibitors of sugar cleavage, and glucagon-like peptide-1 (GLP-1), each of which controls homeostasis of blood sugar by a different mechanism. Common drawbacks of these drugs include side effects, decreased efficacy over time, low cost-effectiveness and only partial anti-diabetic effect of each individual drug. Secretagogues that have the ability to prevent adverse effects (e.g., weight gain, hypoglycemia) or stimulate insulin biosynthesis or protect β-cells from death are rare (Krentz et al., 2005; Purnell et al., 2003). Glucagon-like peptide-1 (GLP-1), an injectable peptide drug, may be the only one reported to fit these criteria (Egan et al., 2003). In view of patients' welfare, there is still a need for development of anti-diabetics for decrease in hypoglycemia, enhancement of insulin synthesis and β-cell protection.
Plants are an extraordinary resource for anti-diabetic remedies. One prestigious example may be metformin, a derivative of the phytochemical, guanidine, from French lilac and known as the insulin sensitizer for T2D. A plant from the Asteraceae family, Bidens pilosa, which was anti-diabetic in alloxan-treated mice, has been used to treat patients with diabetes in America, Africa, and Asia. Two polyacetylenes from B. pilosa have since been demonstrated to be anti-diabetic by different laboratories (Chang et al., 2004, Ubillas et al., 2000). Cytopiloyne was recently identified as the most potent polyacetylene in B. pilosa in prevention of type 1 diabetes via T-cell regulation (Chang et al., 2007). B. pilosa and its three polyacetylenes showed glucose-lowering activities in diabetic mice (Chien et al., 2009; Hsu et al., 2009; Ubillas et al., 2000). However, the anti-diabetic mechanism of these three polyacetylenes is not known.